The Patriots have reached agreement on a one-year deal with free-agent offensive tackle LaAdrian Waddle, according to a league source. The 6-foot-6, 315-pound Waddle becomes one of the most experienced options to possibly replace Nate Solder as the team’s starting left tackle. Here is a closer look at the deal:

Grade: B-plus. Respected offensive line coach Dante Scarnecchia had high praise for Waddle last season. Last November during the bye week, he said of both Waddle and fellow backup Cameron Fleming, “They have the ability to start for a lot of teams, including this team. They just find themselves behind two good tackles [in Solder and Marcus Cannon].” With Solder now with the Giants, and Fleming possibly signing elsewhere as a free agent, Waddle no longer faces that type of logjam on the depth chart.

What it means: The Patriots have Waddle, 2017 undrafted free-agent Cole Croston, second-year player Antonio Garcia and six-year veteran Matt Tobin on the left tackle depth chart, and could still select a player at that position in the draft. While it’s possible that right tackle Marcus Cannon could flip to the left side, that comes with some risk because his career has elevated since the club decided to lock him in solely on the right side. Overall, this is an important signing for the Patriots because it helps build depth at an important position; as 2018 showed, they used all four of their offensive tackles.

What’s the risk: This shouldn’t be a big financial deal, and so the main risk is the term. If Waddle performs well at left tackle, he will be a free agent next season and it will likely be more expensive to retain him. Then again, similar to Tobin, that would be a “high class problem” because it would mean Waddle was a value signing in 2018.

The Patriots have reached agreement with linebacker Marquis Flowers on a one-year deal, according to ESPN’s Adam Schefter. Flowers adds depth on defense and is a core player on special teams. Here is a closer look at the signing:

Grade: B. This deal is consistent with the team’s general philosophy of having a strong middle class on the roster, as Flowers has proven to be a capable fill-in on defense when called upon, carving out a niche in the dime package, and also fills some key roles in the kicking game. Schefter reports the deal has a maximum value of $2.55 million. An estimated cap charge of $1.5 to $2 million seems realistic from the Patriots’ perspective based on Flowers’ likely role.

Marquis Flowers has been a solid fill-in on defense and a key contributor in the kicking game for the Patriots. Kirt Dozier-USA TODAY Sports

What it means: On defense, this shouldn’t change the team’s approach in the draft, where targeting an off-the-line linebacker figures to be a high priority. Meanwhile, special-teams coach Joe Judge is probably smiling. Flowers plays on the punt protection unit and the front line on the kickoff return unit. Depending on how involved he is with the defensive plan, Flowers could also play on the punt return and kickoff coverage units. This also means that the Patriots potentially could get a second year on their investment in trading for Flowers last year, when they sent a seventh-round pick to the Bengals for him.

What’s the risk: Economics. The Patriots invest as much in core special-teams personnel as any team in the NFL, and in doing so it potentially limits their opportunities to make other moves. It’s all part of the puzzle of putting a team together in the salary-cap era.

The Patriots have agreed to terms with special teams captain Matthew Slater on a two-year deal, which ensures one of their top leaders is back in the fold. Here is a closer look at the signing:

Grade: A. While Slater has battled injuries the last two seasons, missing 10 regular-season games, his locker-room presence and mentorship to younger players is invaluable. That alone makes this an important move for the club. Slater had visited the Steelers a few days ago, and seeing a locker-room pillar like him depart for Pittsburgh would have been a tough blow for Patriots fans to absorb.

Special teams ace Matthew Slater brings value on the field and in the locker room. Photo by Kevin C. Cox/Getty Images

What it means: The Patriots have some of the best special teams personnel in the NFL, led by Slater, newly-acquired Cordarrelle Patterson, Nate Ebner, Brandon Bolden and Brandon King. This highlights how the Patriots invest significant resources in a core special teams group. Last year, during one of his weekly film breakdowns on Patriots.com, Bill Belichick pointed out how Slater drew extra attention from the opposition. That was a good example of how on-field presence made others around him better.

What’s the risk: Slater turns 33 in early September, has top-end speed, but has been slowed of late with some hamstring injuries. The risk would be if those injuries persist, limiting Slater’s effectiveness.

The Patriots have agreed to terms with free-agent offensive tackle Matt Tobin on a one-year deal, which highlights how they are in transition mode at left tackle after their starter since 2011, Nate Solder, signed with the Giants in free agency. Here's a closer look at the Tobin signing.

Grade: B-minus. Tobin played in college at Iowa under Kirk Ferentz, who is one of Bill Belichick's closest coaching confidants. The idea that he's a potential replacement for Solder could be a reach, but he'll be put into the mix and will be given a chance to prove himself at a position that is arguably the team's biggest question mark. Line coach Dante Scarnecchia has a solid history of developing athletic linemen like the 6-foot-6, 303-pound Tobin.

Matt Tobin will get a chance to compete for the Patriots' vacant starting left tackle spot. Bill Streicher/USA TODAY Sports

What it means: The Patriots are in the process of building depth across their roster and Tobin joins 2017 undrafted free agent Cole Croston (also of Iowa) and 2017 third-round pick Antonio Garcia at left tackle. Garcia spent all of last season on the non-football illness list, and it's unknown how much he'll be able to contribute in 2018. The Patriots could still re-sign LaAdrian Waddle and Cameron Fleming -- their two backups from last season -- and could also look to the draft.

What's the risk: The one-year term means that if Tobin emerges as a capable starter, the team could be in the same position in 2019 as it currently is in terms of replacing a starting player. Of course, that would fall into the "high-class problem" category because it would mean Tobin turned into a great value signing in 2018. This is a limited-risk move.

The New England Patriots have agreed to terms with free-agent running back Jeremy Hill, who played the first four years of his career with the Bengals after being selected in the second round of the 2014 draft out of LSU. Here is a closer look at the signing, which was first reported by ESPN’s Field Yates.

Grade: B-minus. Hill was highly regarded coming out of the '14 draft and has faded a bit off the radar, so this is a case of the Patriots identifying a potential undervalued asset in the marketplace who could benefit from a change of scenery. They’ve had some success with that approach in the past, and while contract terms are not known, it’s hard to imagine this will put much stress on their salary cap.

Jeremy Hill was highly regarded coming out of the 2014 draft and has faded a bit off the radar. A change of scenery could do him good. Patrick Smith/Getty Images

What it means: Hill becomes the biggest running back on the Patriots' roster, at 6-foot-1 and 230 pounds, and could challenge Mike Gillislee for the top power role. The Patriots also re-signed Rex Burkhead to a three-year deal in free agency, and he’s a dual threat, while James White is the capable and clutch third-down back. Veteran Brandon Bolden, whose primary contributions come on special teams, adds insurance. Patriots coach Bill Belichick talked last year about the value of having multidimensional backs who can put stress on a defense with both their rushing ability and pass-catching skills, and Hill has totaled 67 career receptions, so he’s not a run-only option. His addition to the roster brings another level of competition, which is never a bad thing.

What’s the risk: Ball security. Belichick often says that when a player has the football in his hands, he carries the fate of the entire team with it. And Hill has had some ball-security struggles in his career; his time with the Bengals took a turn of sorts after his costly playoff fumble against the Steelers two seasons ago. He is also coming off a season in which he played in only seven games because of an ankle injury.

The Patriots have agreed to terms with free-agent defensive end Adrian Clayborn, who has played with the Buccaneers (2011-2014) and Falcons (2015-2017). Here’s a closer look at the signing.

Grade: B. After a 2016 season in which the Patriots had an effective four-man rotation at defensive end, the position was a trouble spot for them in 2017 after trades for Kony Ealy and Cassius Marsh flopped and Rob Ninkovich retired. That put too much burden on the team’s best player at the position, Trey Flowers. Building better depth has to be a priority in 2018, and the 6-foot-3, 280-pound Clayborn helps the Patriots take a step in that direction.

The Patriots hope Adrian Clayborn can give their pass rush a shot in the arm. Mark LoMoglio/Icon Sportswire

What it means: Clayborn, who has 30 career regular-season sacks, could help boost the team's pass rush. The need for more pressure was most recently evident in Super Bowl LII. Clayborn had 9.5 sacks last season, which could be viewed as him still being able to get after it, although six came in one game against overmatched Dallas blockers Chaz Green/Byron Bell. Specific to the Patriots, they are now on the board in compensatory free agency, as this is the first player they've signed who played for another team. Because they've lost five compensatory free agents and signed only one, it won't affect the formula that determines 2019 compensatory draft picks, as the Patriots are projected to receive four overall selections (via Nick Korte of OvertheCap.com).

What's the risk: Clayborn is coming from a pure 4-3 defense in Atlanta, which is significantly different from what the Patriots run, so there is a projection as to how he will fit. The Patriots' failed trade for Ealy last year is a reminder of how challenging that type of transition can be for some players to make. But one aspect that might have given Bill Belichick comfort in signing Clayborn is that he had a fairly productive 2013 season in Tampa under Greg Schiano, one of Belichick's close friends in the coaching profession. One other risk: Clayborn’s injury history (knee in 2012, biceps in 2014).

The New England Patriots have agreed to a multi-year contract extension with running back Rex Burkhead, who spent the 2017 season with the team and was scheduled to be an unrestricted free agent. Terms of the deal were not disclosed. Here's a closer look at the signing:

Grade: B. With No. 1 option Dion Lewis departing for the Titans on a lucrative four-year, $23 million pact ($11.5 million in guarantees), the Patriots ensured that the third option on their depth chart from last year is sticking around on what figures to be a deal at a lower financial level. Once financial terms are learned, it will be easier to assess the deal.

Rex Burkhead rushed for 264 yards last season and caught 30 passes for another 254 yards. Getty Images

What it means: The Patriots will likely still explore running back options in the draft, where they haven't chosen a player at the position since 2014, but they now have Burkhead, James White and Mike Gillislee under contract at the position and won't have to force it. The team has shifted toward multi-dimensional running backs who are factors as both rushers and pass-catchers, and Burkhead (30 receptions in 2017) fits the mold well.

What's the risk: Injuries. The 5-foot-10, 210-pound Burkhead missed six games in the regular season last year with rib and knee ailments, and also was held out of the divisional-round playoff win over the Titans. Just as the Patriots might have been reluctant to make a big investment in Lewis because of his injury history, they likely had the same discussion as it relates to Burkhead, albeit at a projected lower financial level.